When a corpse with its fingerprints removed is found crushed under a gravel-pile avalanche, Em Hansen gets on the case in Andrews's 10th mystery to feature the Utah forensic geologist (after 2004's Earth Colors ). An unmistakable tattoo allows Em to identify the victim as Afton McWain, but what was the eccentric Colorado environmental activist doing in Salt Lake? Em hitches a ride with Fritz Calder, a charter-plane pilot friend, to Colorado, where McWain's ex-wife and current live-in "nature girl" reside. No love is lost between the suspicious pair, who both consider themselves heir to McWain's off-the-grid ranch, which is surrounded by hungry developers whose financial interests don't mesh with his findings about water availability in this drought-stricken region. As Em and Fritz weather their way through missed romantic signals, ominous clouds gather over the ranch, where Em collects evidence. Andrews may wander from scientific dissertations to romantic reveries and inadequately fleshed-out subplots, but fans of information-packed suspense should be satisfied. (Dec.)